Two-Cycle Diesel Engine Configured for Operation with High Temperature Combustion Chamber Surfaces

ABSTRACT

A 2-cycle, direct-injection diesel engine configured to accommodate low cetane diesel and jet fuels. The engine includes combustion chambers having surfaces which are operable at high temperatures during engine operation to increase the combustion rate of low cetane fuels. The engine is further configured to reduce starting times in cold and/or low pressure situations such as those experienced during attempts to restart a plane engine at relatively high altitudes.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/577,728, filed on Sep. 20, 2019, which is a continuation of U.S.patent application Ser. No. 16/224,281, filed on Dec. 18, 2018, now U.S.Pat. No. 10,458,307, which is a continuation of InternationalApplication No. PCT/US2016/039853, filed on Jun. 28, 2016, which areincorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

The present invention generally relates to a two-cycle, diesel engine.In particular, the invention relates to a novel, diesel engineconfiguration permitting operation of the engine with combustion chambersurface temperatures which allow the engine to properly function whileusing diesel fuels having a range of cetane (also referred to ashexadecane) levels. The engine configuration also permits restarting ofthe engine at low atmospheric pressures of the type experience whenusing the engine for aviation applications.

SUMMARY OF THE INVENTION

One embodiment of the invention relates to a two-cycle diesel engine foroperating with high combustion chamber surface temperatures. The engineincludes an aluminum engine block including at least one cylinderincluding a first intake port and a first exhaust port. The engine blockincluding a first fluid flow channel for cooling the engine block and asecond fluid flow channel located at the exhaust port to cool theportion of the cylinder proximate the exhaust port. The engine alsoincludes a cylinder sleeve having a top end and a bottom end, andfabricated from a metal composite to include a second intake port and asecond exhaust port proximate the bottom end. The sleeve being fastenedto the interior of the cylinder with the intake ports being in fluidcommunication and the exhaust ports being in fluid communication. Theengine also includes a head assembly engaged with the engine block, thehead assembly including a third cooling fluid flow channel. The enginealso includes a fuel injector assembly including an injector tip. Theassembly is supported by the head assembly. The injector assemblyincluding a fuel flow channel between a fuel source and the injectortip, a return fuel channel between the injector tip and the fuel sourceand a cooling fuel channel between the injector tip and the fuel source.The engine also includes a stainless steel fire plate resilientlysupported between the top end of the cylinder sleeve and the headassembly to cooperate with the fuel injector assembly to close the topend of the cylinder sleeve. The engine also includes a crank shaftcoupled to a connecting rod. The engine also includes an aluminum pistonhaving a titanium alloy crown, the piston being located within thesleeve. The piston connected to the connecting rod to move the crownbetween the top of the cylinder sleeve, and below the second intake andexhaust ports. The engine also includes a turbocharger including aturbine coupled to the exhaust ports and a compressor. The compressorincluding an input coupled to an air filter and an output. The enginealso includes a supercharger including a compressor coupled to thecompressor output and the intake ports.

Another embodiment of the Invention relates to a two-cycle diesel enginefor operating with high combustion chamber surface temperatures. Theengine includes an aluminum engine block including at least fourcylinders each including a first intake port and a first exhaust port.The engine block including a first fluid flow channel for cooling theengine block and a second fluid flow channel located at the exhaustports to cool the portions of the cylinders proximate the exhaust ports.The engine also includes at least four cylinder sleeves each having atop end and a bottom end. The cylinder sleeves fabricated from a metalcomposite to each include a second intake port and a second exhaust portproximate the bottom ends. The sleeves being fastened to the interior ofa respective cylinder with the intake ports being in fluid communicationand the exhaust ports being in fluid communication. The engine alsoincludes at least four head assemblies engaged with the engine block,the head assemblies each including a third cooling fluid flow channel.The engine also includes at least four fuel injector assemblies eachincluding an injector tip. The assemblies are each supported by arespective head assembly. The injector assemblies each including a fuelflow channel between a fuel source and the injector tip, a return fuelchannel between the injector tip and the fuel source and a cooling fuelchannel between the injector tip and the fuel source. The engine alsoincludes at least four stainless steel fire plates. Each of the fireplates is resiliently supported between the top end of respectivecylinder sleeves and the head assemblies to cooperate with the fuelinjector assembly to close the top end of a respective cylinder sleeve.The engine also includes a crank shaft coupled to at least fourconnecting rods. The engine also includes at least four aluminum pistonseach having a titanium alloy crown. The pistons are located within arespective sleeve and connected to a respective connecting rod to movethe crown between the top of the cylinder sleeve, and below the secondintake and exhaust ports. The engine also includes a turbochargerincluding a turbine coupled to at least one of the exhaust ports. Theturbocharger also includes a compressor including an input coupled to anair filter and an output. The engine also includes a superchargerincluding a compressor coupled to the output and at least one of theintake ports.

Another embodiment of the invention relates to an engine unit. Theengine unit includes an engine block including at least one cylinder.The at least one cylinder includes a first intake port and a firstexhaust port. The engine block includes a first fluid flow channel forcooling the engine block and a second fluid flow channel located at theexhaust port to cool the portion of the cylinder proximate the exhaustport. The second fluid flow channel includes a first branch passing overthe top portion of the first exhaust port and a second branch passingunder the bottom portion of the first exhaust port. The engine unit alsoincludes a cylinder sleeve having a top end and a bottom end. The topand bottom end fabricated from a metal composite to include a secondintake port and a second exhaust port proximate the bottom end. Thesleeve is fastened to the interior of the cylinder with the intake portsbeing in fluid communication and the exhaust ports being in fluidcommunication. The engine unit also includes a head assembly engagedwith the engine block. The head assembly includes threads for engagingthe head to the engine block and including a third cooling fluid flowchannel. The engine unit also includes a fuel injector assemblyincluding an injector tip. The assembly is supported by the headassembly. The injector assembly includes a fuel flow channel between afuel source and the injector tip, a return fuel channel between theinjector tip and the fuel source and a cooling fuel channel between theinjector tip and the fuel source. The engine unit also includes astainless steel fire plate. The engine unit also includes a deflectedbelleville washer. The belleville washer is located between the headassembly and the stainless steel fire plate. The engine unit alsoincludes a sealing washer. The sealing washer is located between thestainless steel fire plate and the top end of the cylinder sleeve. Thesealing washer, fire plate and fuel injector assembly are arranged toclose the top end of the cylinder sleeve. The engine unit also includesa crank shaft coupled to a connecting rod. The engine unit also includesan aluminum piston having a titanium alloy crown. The piston is locatedwithin the sleeve and connected to the connecting rod to move the crownbetween the top of the cylinder sleeve, and below the second intake andexhaust ports. The engine unit also includes a wrist pin supported atits ends and center by the piston. The end of the connecting rodincludes a saddle which surrounds less than 180 degrees of the wrist pinand is fastened to the wrist pin. The engine unit also includes aturbocharger including a turbine coupled to the exhaust ports and acompressor including an input coupled to an air filter and an output.The engine unit also includes a supercharger including a compressorcoupled to the compressor output and the intake ports.

Alternative example embodiments relate to other features andcombinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

This application will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, wherein like reference numerals refer to like elements inwhich:

FIG. 1 is an elevational view of an internal combustion engine in whichthe present invention is employed.

FIG. 2 is a sectional view taken along line II-II illustrating acylinder head, a cylinder, a piston and a connecting rod of the engineof FIG. 1.

FIG. 3a is a cross-sectional view taken along line III-III of FIG. 2.

FIG. 3b is a top perspective view of a crown the piston of FIG. 2

FIG. 3c is a perspective cross-sectional view of the piston and crown ofFIG. 2

FIG. 4 is a schematic of a fuel injection system for the engine of FIG.1.

FIG. 5 is a cross-sectional view taken along line VII-VII of FIG. 8.FIG. 5 is also an enlarged view of a portion of FIG. 2 illustrating ingreater detail the cylinder, the cylinder head, the fuel injector andthe cooling cap.

FIG. 6 is a perspective view of a fuel injector body of the engine ofFIG. 1.

FIG. 7 is a cross-sectional view taken along line V-V of FIG. 6.

FIG. 8 is a top-view of FIG. 5.

FIG. 9 is an elevational view of another internal combustion engine inwhich the present invention is employed.

FIG. 10 is a partial sectional view of a portion of the engine shown inFIG. 9.

FIG. 11 is an exploded perspective view of certain components of theengine of FIG. 9 and as further shown in FIG. 10.

FIG. 12 is an enlarged view of a portion of FIG. 10.

FIG. 13 is a top view of a cylinder head and cooling cap according toanother embodiment of the invention.

FIG. 14 is a cross-sectional view taken along line XV-XV of FIG. 13.

FIG. 15 is a top down view of the engine block having the cylinder headsremoved and cut to see the flow path of the exhaust pipe cooling system.

FIG. 16 is a cross-sectional view taken along line XVI-XVI of FIG. 15.

FIG. 17 is a perspective view of a crankcase pressure regulator of theengine of FIG. 1.

FIG. 18 is a partial cross-sectional side view of the crankcase pressureregulator of

FIG. 17 taken along line III-III of FIG. 17.

FIG. 19 is an oil flow diagram of the engine of FIG. 1.

FIG. 20 is an air flow diagram of the engine of FIG. 1.

DETAILED DESCRIPTION

The engine configuration discussed in detail below uses variouscombinations of engine component configurations and materials whichpermit operation of an engine using combustion temperatures which allowthe engine to properly function while using diesel fuels of varyingcetane content. Of particular concern are diesel fuels with low cetanelevels. For example, the ASTM D1655 standard for Jet A type fuel doesnot control for cetane levels, which results in high cetane variationamongst different sources of the same Jet A fuel type. The cetane numberis an indicator of the combustion speed of diesel fuel as typicallymeasured by the time period between the start of injection and the firstidentifiable pressure increase during combustion of the diesel fuel.Higher cetane fuels will have shorter ignition delay periods than lowercetane fuels. By way of reference, the characteristic diesel “knock”occurs when fuel that has been injected into the cylinder ignites aftera delay causing a late shock wave. Minimizing this delay results in lessunburned fuel in the cylinder and less intense knock. Thereforehigher-cetane fuel usually causes an engine to run more smoothly andquietly.

Generally, diesel engines operate well using diesel fuel having a cetanenumber between 40 to 55. In Europe, diesel cetane numbers were set at aminimum of 38 in 1994 and 40 in 2000. The current minimum in the EU is acetane number of 51. In North America, most states have adopted aminimum cetane number for diesel fuel of 40, with typical values in the42-45 range. By way of further example, California requires that dieselfuel have a minimum cetane of 53.

One embodiment of the engine is configured for use as an aircraftengine. When used in aircraft, the diesel fuels available at variousairports will vary and may have cetane levels which are low enough toproduce poor engine performance. However, the ignition delays caused bylow cetane levels can, within a range, be compensated for by increasingthe combustion temperatures of a diesel engine. However, increasing thecombustion surface temperature to a level effective to produce suchcompensation is not merely a matter of just allowing an engine to runhotter. Rather, the increased temperature requires an engine which isconfigured to provide proper heat removal from the engine whilepermitting increased localized temperatures in a combustion chamberconfigured to operate at higher temperatures and configured to causemixing and movement/flow of a fuel-air mixture to improve ignition at agiven temperature. The novel engine configuration disclosed hereinprovides for a two-cycle diesel engine which can properly function atcetane levels as low as 28.

Illustrated in FIG. 1 is an internal combustion engine 10. The engine 10is a two-stroke, diesel engine having four cylinders 22 in a V-typearrangement operable to drive a propeller 411 (see FIG. 20). Engine 10(and version 310 discussed further below) generally is a four cylinderengine wherein diesel fuel is direct injected directly at the top andcenter of each cylinder. One structural feature of engine 10, whichpermits this direct injection, is that engine 10 does not include eitherexhaust or intake valves. Rather, intake and exhaust ports are locatedin the cylinder and sleeve walls so that engine 10 exhausts and intakesfresh combustion air when the piston 26, 330 is at or near the bottom ofits stroke. To improve performance and efficiency of engine 10, asupercharger 1, an intercooler 2 and a turbocharger 3 are used (shownschematically in FIGS. 1 and 9). In particular, the turbocharger 3 iscoupled to the exhaust ports and powered by the exhaust energy from thecylinders. The supercharger 1 is located between the cylinders 22 and iscoupled between the input ports of engine 10 to further pressurize thefresh air entering the cylinders of engine 10 during operation.Intercooler 2 is coupled to the output of turbocharger 3 and the inputof supercharger 1. In addition to improving engine performance, theaddition of supercharger 1 in combination with turbocharger 3 andintercooler 2 reduces the time for engine starting and restarting. Inone embodiment, the supercharger 1 starts the flow of gas in engine 10and spools up turbocharger 3, which lessens the amount of work requiredof supercharger 1. By way of specific example, for aircraftapplications, engines may need to be restarted during flight. In thissituation, short restart times are desirable. Ideally, restart times areshorter than the time it takes for a plane to make an unintendedlanding.

Referring to FIG. 2, engine block 14 at least partially defines acrankcase 18 and two sets of two cylinders (only two of the cylinders 22are shown in FIG. 1 and are labeled 22a and 22b. Unless a descriptionrequires specific reference to a particular cylinder, the cylinders willbe referred to only with reference numeral “22”). The four cylinders 22are generally identical, and only one cylinder will be described indetail. A crankshaft (not shown) is rotatably supported within thecrankcase 18 by pressure lubricated bearings. A piston 26 reciprocatesin the cylinder 22 and is connected to the crankshaft via connecting rod30. As the piston 26 reciprocates within the cylinder 22, the crankshaftrotates.

The connecting rod 30 includes a first end 34 which is connected to thecrankshaft. The connecting rod 30 further includes a second end 38 whichincludes an arcuate portion 42 that does not completely encircle a wristpin 46. Preferably, the arcuate portion 42 of the connecting rod 30 hasan arcuate extent that is about or slightly less than 180 degrees. Thewrist pin 46 has an annular wall 50 including a cylindrical innersurface 54 (FIG. 3a ) and a cylindrical outer surface 58, which engagesthe arcuate portion 42 of the connecting rod 30, and is pivotallyconnected to the piston 26. A plurality of fasteners 62 extend throughthe annular wall 50 of the wrist pin 46 and into a wrist pin insert 66(see also, FIG. 3a ) to secure the wrist pin 46 to the arcuate portion42 of the connecting rod 30. Preferably, the wrist pin insert 66 iscylindrical or trunnion type wrist pin. Using a trunnion type wrist pinincreases the available bearing area. Preferably, the fasteners 62 arescrews and thread into the wrist pin insert. This connecting rodarrangement permits the top portion of the piston to have moreuniformity than a connecting rod arrangement wherein end 38 surroundsthe wrist pin 46. In the arrangement where end 38 surrounds theassociated wrist pin 46, material is removed from the top portion of thepiston 26. The removed material changes the deformation characteristicsof the piston 26 when it is heated and cooled during engine operationeither during transient periods or as the engine cycles through itsdiesel combustion cycle.

Additionally, as shown in FIG. 3a , where the upper or second end 38 ofthe connecting rod 30 does not encircle the wrist pin 46, the piston 26bears against the wrist pin 46 along the entire top of the wrist pin 46,thereby more evenly distributing the load on the wrist pin 46. The useof the wrist pin insert 66 further increases the strength and stabilityof the wrist pin 46. The forced rocking of the wrist pin 46 as theconnecting rod 30 pivots and the increased bearing surface area of thewrist pin 46 minimizes uneven wear on the bearing surface of wrist pin46 during operation of the engine 10.

Referring now more specifically to the top of piston 26, FIG. 3b is atop perspective view of a crown 27 of piston 26 and FIG. 3c is aperspective cross-sectional view of the piston showing the configurationof crown 27. In particular, crown 27 includes the arcuate grooves 29.Grooves 29 cause improved mixing of the fuel air mixture during theinitial combustion of the mixture which increases the combustion speedfor fuel having a given cetane level. When combined with the otherstructural features of engine 10, grooves 29 improve the performance ofengine 10 when burning low cetane diesel fuels.

As generally discussed above, engine performance for fuels having agiven cetane level is also improved if the surface temperatures of thesurfaces defining the interior combustion chamber (generally referencedas 74 in FIGS. 2, 5, 12 and 14, and as 350 in FIG. 10) are maintainedsufficiently high. Accordingly, these surfaces must be fabricated orformed from materials which are suitable for use in an engine at highoperating temperatures. The first of these surfaces is the top surfaceof crown 27. A suitable material for use in fabricating crown 27 is atitanium metal. By way of specific example, for the engine 10 asdisclosed herein it is desirable to use a titanium compound such as Ti6Al-4V. This example alloy by weight percentage includes Carbon (maximum0.10%), Aluminum (5.50 to 6.75%), Vanadium (3.50 to 4.50%), Nitrogen(approximately 0.05%), Iron (maximum 0.40%), Oxygen (maximum 0.020%),Hydrogen (maximum 0.015%), Other (maximum 0.40%), and balance Titanium.

The grooves 29 are formed into the top of crown 27. In one embodiment, aball end mill is used to cut out grooves 29. The crown 27 is joined toskirt 31 of piston 26. In one embodiment, threads are formed on theinterior of crown 27 that are configured to mate with threads formed onskirt 31. Crown 27 is further staked at three different locations.Accordingly, the shape of and material used for crown 27 provide one ofthe surfaces which define the interior of combustion chamber 74. Thissurface is designed to both improve fuel air mixing and be useable at asurface temperature which is suitable for burning lower cetane fuels.

Referring to FIG. 4, engine 10 includes four fuel injectors 70 a, 70 b,70 c and 70 d, one for each cylinder 22. (Unless a description requiresspecific reference to a particular fuel injector, fuel injectors will bereferred to only with reference numeral “70.”) Fuel injectors 70 aresubstantially identical to each other, and only one will be described indetail. Referring generally to FIG. 5, fuel injector 70, is located toinject fuel into a combustion chamber 74 which has an internal surfacedefined by the surfaces of piston crown 27, a cylinder sleeve 322, andfireplate 338. The fuel injector 70 includes a fuel injector nut 86which is received by an appropriately sized tapered bore in a cylinderhead 78. Inside the injector nut 86 is a fuel injector tip 90 housing apressure responsive, movable pintle (not shown). The nut 86 and the tip90 define a main fuel outlet 92 communicating with the combustionchamber 74. A fuel injector body 82 is threaded into the upper end ofthe nut 86.

Referring to FIGS. 6 and 7, the fuel injector body 82 includes a mainfuel inlet port 98 which communicates with and transitions into fuelpassage 106. A fuel inlet cooling port 110 communicates with andtransitions into a cooling port 118. An injector overflow fuel outletport 114 communicates with and transitions into outlet port 120.Although not shown, the fuel injector further includes a flowstraightener, a check valve, a check valve receiver, a spring mechanismand a spring guide, all of which are positioned within a hollow space 94of the fuel injector nut 86 between the body 82 and the tip 90. Theaddition of the inlet cooling port 110 and the cooling port 118 allowscooling of the fuel injector as described below.

FIG. 4 illustrates a fuel flow schematic for a fuel injection system122. Shown is fuel supply tank 126, fuel line 128, fuel filter 130, fuelpump 132 which includes delivery pump 134 and high pressure pump 138,and fuel lines 142 connected to the fuel inlet ports 98 of the injectorbodies 82 of the injectors 70. Fuel line 146 is connected to the coolingport 110 of injector 70d. Ports 114 and 110 of injectors 70d and 70c arein fluid communication, ports 114 and 110 of injectors 70c and 70b arein fluid communication and ports 114 and 110 of injectors 70b and 70aare in fluid communication. Port 114 of injector 70a is connected toreturn fuel line 148. The fuel flowing through ports 98, 110, and 114mixes in space 94 and provides for a fuel flow through at least threelocations in injector body 82 to maintain the injector body at atemperature which is approximately the average temperature of the fuelin space 94.

Referring to FIGS. 2, 5 and 10, it can be seen that the injectors areengaged and in thermal contact with the cylinder head 78, 342 and inthermal contact with fireplate 338 (if used). As a consequence, theadditional cooling provided by cooling ports 110 and 118 allow engine 10to operate with relatively high surface temperatures on the surfaces ofchamber 74. Without these ports, the surface temperatures would need tobe lower to prevent over heating of body 82 and the fuel which flowsthrough body 82. By providing an injector with additional cooling,combustion chamber 74 temperatures for burning lower cetane fuels aremore readily achieved. In addition, the warmed overflow fuel will warmall of the fuel in the system which serves to limit jelling of the fuelat cold temperatures of the type experienced in cold weather or at highaltitudes.

FIGS. 5 and 8 illustrate a cooling cap 154 mounted on the cylinder head78 to cool the cylinder head 78. The cooling cap 154 has an annularcoolant groove 158 which mates with an annular coolant groove 162 of thecylinder head 78 to define an annular cooling passageway 166 when thecooling cap 154 is mounted on the cylinder head 78. In otherembodiments, such as the embodiment which is illustrated in FIGS. 9-12,only one of the cooling cap 154 and the cylinder head 78 includes agroove such that the combination of the cooling cap 154 and the cylinderhead 78 define the annular cooling passageway 166. The cooling cap 154includes inlet port 170 and outlet port 174 which communicate with theannular cooling passageway 166, so that cooling fluid can flow into theinlet port 170, through the annular cooling passageway 166 and out theoutlet port 174, thereby cooling the cylinder head 78. As used withinthe claims, “substantially annular” includes an enclosed loop similar tothat illustrated in FIGS. 5 and 8, and a partial loop similar to thatillustrated in FIGS. 9-12 (e.g., an annular groove that is separated bya divider pin, or projection 406).

The engine block 14 includes a cooling jacket 178 with an outlet 182 andan inlet (not shown). The cooling cap 154 is placed on the cylinder head78 with the inlet port 170 in alignment with the outlet port 182 of thecooling jacket 178 and the outlet port 174 in alignment with the inletport of the cooling jacket 178. A first transfer tube 186 communicatesbetween the inlet port 170 of the cooling cap 154 and the outlet port182 of the cooling jacket 178, and a second transfer tube (not shown)communicates between the outlet port 174 of the cooling cap 154 and theinlet port of the cooling jacket 178.

As shown in FIG. 8, the inlet port 170 and the outlet port 174 of thecooling cap 154 are not diametrically opposed around the annular coolingpassageway 166. Thus, a first portion of the annular cooling passageway166 extends in one direction from the inlet port 170 to the outlet port174 (representatively shown as arrow 190 in FIG. 8) and a second portionof the annular cooling passageway 166 extends in an opposite directionfrom the inlet port 170 to the outlet port 174 (representatively shownas arrow 194 in FIG. 8). The first portion of the annular coolingpassageway 166 is shorter in length than the second portion of theannular cooling passageway 166. The flow rate through the annularcooling passageway 166 in either direction is proportional to thedistance traveled. The first portion of the annular cooling passageway166 is restricted. In this way, cooling fluid travels in both directionsthrough the annular cooling passageway 166 to cool the cylinder head 78.

The cooling cap 154 is adjustably positionable around the cylinder head78, so that the inlet port 170 and the outlet port 174 are properlyalignable with the associated inlet and outlet ports of the coolingjacket 178. This accommodates the cylinder head 78 which threads intothe cylinder block or engine block 14. Engine block 14 includes femalethreads concentric with the cylinder 22, and the cylinder head 78includes male threads which engage the female threads of the engineblock 14. Because the cylinder head 78 threads into the engine block 14,it is not exactly known where the cylinder head 78 will be located withrespect to the engine body. Once the adjustable cooling cap 154 isproperly located on the cylinder head 78, a plurality of clampingmembers 198, preferably equally spaced apart, span across the top of thecooling cap 154 to secure the cooling cap 154 to the cylinder head 78.Each of the clamping members 198 has opposite ends 202 and 206, and issecured to the cylinder head 78 by a pair of fasteners 210. One fastener210 is located adjacent end 202 and the other fastener 210 is locatedadjacent end 206. Preferably, the fasteners 210 thread into the top ofthe cylinder head 78. Preferably, the cylinder head 78 includes aplurality of sets of pre-drilled, threaded holes such that each fastener210 can be located in a plurality of positions relative to the cylinderhead 78. Preferably, end 202 of each clamping member 198 is received byan annular groove 214 in the fuel injector nut 86, thereby also securingthe fuel injector 70 to the cylinder head 78.

In the embodiment illustrated in FIGS. 5 and 8, the coolant initiallyflows from a pump (not shown) into the cooling jacket 178. From thecooling jacket 178, the coolant flows through the outlet port 182 of thecooling jacket 178 into the first transfer tube 186, and then into theinlet port 170 of the cooling cap 154. From the inlet port 170, thecoolant travels through the cooling passageway 166 to the outlet port174 of the cooling cap 154 removing heat from the cylinder head 78. Thecoolant then flows from the outlet 174 of the cooling cap 154 throughthe second transfer tube and inlet port of the cooling jacket 178 toreturn to the cooling jacket 178. From the cooling jacket 178, theheated coolant is returned to the pump of the coolant system to becooled and returned to the cooling jacket 178.

Another embodiment of the cooling cap 154 is illustrated in FIGS. 13 and14. This embodiment is substantially similar to the embodiment shown inFIGS. 5 and 8 except that the embodiment illustrated in FIGS. 13 and 14includes a different coolant flow path. Reference numbers used withrespect to the embodiment illustrated in FIGS. 5 and 8 are also used inFIGS. 13 and 14 to indicate like components.

With reference to FIGS. 13 and 14, the coolant initially flows from apump (not shown), through a supply conduit 172, and into the coolingjacket 178. From the cooling jacket 178, the coolant flows into andthrough the outlet port 182 of the cooling jacket 178, through the firsttransfer tube 186, through the inlet port 170 of the cooling cap 154,and into the annular cooling passageway 166. From the inlet port 170,the coolant travels through the cooling passageway 166 in the directionof arrow 194 to the outlet port 174 of the cooling cap 154 removing heatfrom the cylinder head 78. In this embodiment, the coolant is blockedfrom flowing toward the outlet 174 in a direction opposite to the arrow194. The coolant then flows from the outlet 174 of the cooling cap 154through a second transfer tube 184 and into a return port 188. From thereturn port 188, the coolant is directed back to the pump through thereturn line 192 to be cooled and returned to the cooling jacket 178through the supply conduit 172. As just described, the coolant flowsinto the cooling jacket 178, then flows into the cooling cap 154, andthen returns to the pump. In contrast, the coolant used with theembodiment illustrated in FIGS. 5 and 8 flows into the cooling jacket178, then flows into the cooling cap 154, then flows back into thecooling jacket 178, and then finally returns to the pump.

In one embodiment of engine 10, a cross-feed cooling passageway extendsbetween the respective cooling jackets for the engine cylindersproviding cooling fluid flow between the cooling jackets. The cross-feedcooling passageway may be drilled through the portion of the engineblock 14 supporting the main bearing support for the crankshaft. If athermostat communicating with the one of the cooling jackets 178 fails,the cross-feed cooling passageway enables cooling fluid to continue toflow to minimize or prevent damage to the respective cylinder head. Thecross-feed cooling passageway also reduces the thermal gradient betweenthe cylinder heads and the lower crankcase of the engine to reducedistortion of the aluminum block due to unacceptable temperaturegradients and, thereby increase engine life.

Illustrated in FIG. 9 is another embodiment of the engine, referenced asengine 310. In this embodiment, a cylindrical sleeve 322 is positionedwithin the cylinder 318. The sleeve 322 may be an aluminum sleeve thatis shrink fitted into the cylinder 318 and bonded to the engine block314 with an epoxy resin having an aluminum filler. The sleeve 322includes a shoulder 326. A piston 330 reciprocates within the sleeve322. Preferably, the sleeve would be fabricated from a metal matrix toprovide a wear resistant internal surface at surface temperatures whichpermit efficient combustion of relatively low cetane diesel fuels. Oneexample of such a matrix is a 10S4G Aluminum Composite.Application-10S4G uses a silicon carbide (SiC) particulate and a nickel(Ni) coated graphite for improved wear resistance, continuous lubricityand good high temperature strength. The base alloy of the matrix byweight percent is composed of Silicon (8.5-9.5%), Iron (0.20% maximum),Copper (0.20% maximum), Manganese (0.10% maximum), Magnesium(0.45-0.65%), Zinc (0.10% maximum), Titanium (0.20% maximum), Othermatter (0.05% maximum each and 0.15 maximum total), Aluminum (remainder%). To form the fmal composite SiC and Ni coated graphite are added tothe base alloy. In one embodiment, the SiC is 10% by volume and isnominally 30 microns in diameter, and the Ni coated graphite (e.g.Novamet 60% NCG) is 4% by volume. Then, the combined composite issolution and precipitation heat treated. The fmal composite followingtreatment has specific tensile and yield properties. When measured atroom temperature, the fmal composite has a minimum tensile strength of33 KiloPounds per square inch (KSI) and a minimum yield of 27 KSI. Whenmeasured at approximately 300 degrees Fahrenheit, the final compositehas a minimum tensile strength of 23 KSI and a minimum yield of 20 KSI.

As another suitable alternative, sleeve 322 would be fabricated fromaluminum with a steel coated internal surface. These embodiments providefor another portion of the internal surface of combustion chamber 74which can be maintained at relatively high temperatures during engineoperation to provide improved engine performance with relatively lowcetane diesel fuels. By way of example, the steel coating of sleeve 322is preferably accomplished with steel wire used in a plasma-transferredwire arc process. After the appropriate amount of steel is applied tothe internal surface of the sleeve 322, the surface is honed for usewith an appropriate piston and ring set.

Referring to FIGS. 10-12, a gasket 334 is positioned on the shoulder 326of the sleeve 322. In one embodiment, the gasket 334 is a copper gasket.As will be further explained below, the, gasket 334 acts as both asealing mechanism and a shimming device.

The fireplate 338 is positioned between a cylinder head 342 and thegasket 334. A bottom side 346 of the fireplate 338 cooperates with thecrown 27 of piston 330 and the sleeve 322 to define a combustion chamber350. An annular ledge 354 on the fireplate 338 receives an 0-ring 358 toprovide a seal between the side wall 356 of the fireplate 338 and thecylinder 318. In one design, the cylinder head 342 is made of aluminumand the fireplate 338 is made of stainless steel which provides asurface for chamber 350 which is suitable for use at a relatively hightemperature during engine operation.

A head spring 362 is positioned between the cylinder head 342 and thefireplate 338. A bottom side 366 of the cylinder head 342 has an annulargroove 370 which receives the head spring 362, and a top side 374 of thefireplate 338 has a recess 378 which also receives the head spring 362.The head spring 362 is preferably a belleville spring. The head spring362 is also preferably made of stainless steel. Belleville springs takethe form of a shallow, conical disk with a hole through the centerthereof. A very high spring rate or spring force can be developed in avery small axial space with these types of springs. Predeterminedload-deflection characteristics can be obtained by varying the height ofthe cone to the thickness of the disk.

As can be observed with reference to FIGS. 10-12, the cylinder head 342threads into a portion of the engine block 314. When the cylinder head342 is threaded into the engine block 314, the cylinder head 342compresses the head spring 362 against the fireplate 338 to provide adownward force against the top side 374 of the fireplate 338 to offsetan upward force created by combustion within the combustion chamber 350.The downward force provided by the deflection or deformation of spring362 generates a spring force which resiliently forces fireplate 338 intocontact with the gasket 334, which is forced against shoulder 326 of thesleeve 322 to provide an appropriate combustion seal during operation ofthe engine 310.

The head spring 362 also acts to allow for the expansion and contractionof the relevant mating engine components during changing loading andthermal conditions of the engine 310 without adversely affecting thecombustion seal, much like traditional head bolts act. As noted above,head bolts can be used to provide a clamping force that seals a cylinderhead to an engine block. Because the head bolts are allowed to expandand contract with the associated engine components as the loading andtemperature of the engine varies, the head bolts are capable ofmaintaining the clamping force during operation of the engine. However,the threaded cylinder head 342 does not generally have the stretchingcapabilities of typical head bolts because of its relatively largediameter and short thread length.

As suggested above, the load provided by the head spring 362 can becalculated based on the deflection of the spring 362. A specific amountof deflection translates into a consistent amount of downward force,which ensures a proper combustion seal. In one embodiment, the desireddeflection for the head spring 362, the cylinder head 342 and associatedcomponents are obtained by assembling the components as shown in FIG.11. The threads which hold cylinder head 342 in place can be preloaded.By preloading these threads or head bolts (if a bolted headconfiguration is used) the range of varying force applied to the threadsor bolts is reduced, thus increasing the fatigue life of thesecomponents.

The use of gasket 334 allows for the effective control of the locationof piston 330 relative to fireplate 338 to accurately set the top deadcenter of piston 330 relative to fireplate 338. In particular, gasket334 accommodates the accumulation of a deviation from ideal dimensionsresulting from the combination of the tolerances associated with theengine block 314, the cylinder head 342, the sleeve 322, and the piston330. After the fireplate 338 is positioned on the gasket 334, thecylinder head 342 is threaded into the engine block 314 until such timeas the bottom side 366 of the cylinder head 342 contacts the top side374 of the fireplate 338. Once contact is made between the cylinder head342 and the fireplate 338, the final assembly position of the cylinderhead 342 with respect to the engine block 314 is known. The finalassembly position of the cylinder head 342 is then marked or otherwiserecorded for future reference so that a gasket 334 of appropriatethickness can be selected for final assembly.

Providing a cooling system for the cylinder head 342 allows thecombustion chamber surfaces to operate at sufficiently high temperaturesto accommodate low cetane fuels. A cooling cap 382 is mounted on thecylinder head 342. The cooling cap 382 cooperates with an annular groove390 of the cylinder head 342 to define a cooling passageway 394. Thecooling cap 382 includes an inlet port 398 and an outlet port 402. Theinlet port 398 is adapted to receive a cooling fluid flowing through theengine 310, and the outlet port 402 is adapted to send the cooling fluidon through the engine 310 after the cooling fluid has been used to coolthe cylinder head 342. As best shown in FIG. 10, the inlet port 398 andthe outlet port 402 are adjacent to one another. A divider pin 406, orprojection extends from the cooling cap 382 into the cooling passageway394 (see FIG. 12) to substantially close the short passageway betweenthe inlet port 398 and the outlet port 402. In this way, the coolingfluid is only allowed to flow around the cooling passageway 394 in asingle direction to cool the cylinder head 342. Although allowing thecooling fluid to flow in both directions around the cooling passageway394 between the inlet port 398 and an outlet port 402 would cool thecylinder head 342, it has been determined that causing the cooling fluidto flow in one direction around substantially the entire coolingpassageway 394 also provides effective cooling. In other embodiments,the divider pin 406 is eliminated and only a partial annular groove isformed in the cylinder head 342 and/or the cooling cap 382 such that thecombination of the cylinder head 342 and the cooling cap 382 define aunidirectional cooling passage without the need for a divider pin 406.In a further embodiment, divider pin 406 is configured to allow someportion of cooling fluid to flow into the short passageway between theinlet port 398 and the outlet port 402. Allowing cooling fluid to flowinto the short passageway maintains a substantially uniform coolingaround the cylinder head 342.

The manner of attaching the cooling cap 382 to the cylinder head 342 issubstantially described above in relation to engine 10. Reference isalso made to the description above in relation to engine 10 for thedescription and manner of operating the fuel injector 410. In oneembodiment engine 310 includes nine sets of holes 414 for the associatedclamping members 418, as compared to the six sets of holes as shown forengine 10. It was determined that nine sets of holes enables easierpositioning of the cooling cap 382 with respect to the cylinder head342. In an alternative embodiment, cooling cap 382 is fastened tocylinder head 342 with 3 clamping members 418. In this embodiment, theexternal most holes from the set of holes 414 are omitted and only theinterior nine holes are needed to position cooling cap 382 with respectto the cylinder head 342.

Referring now to FIG. 15, a top down view of one side of the engineblock 14 having the cylinder heads removed and cut perpendicularlyacross is shown. Each cylinder head 22 includes a corresponding exhaustpipe a first exhaust pipe 600 in communication with one of the cylinders22 and a second exhaust pipe 602 in communication with a different oneof the cylinders 22 are shown in FIG. 15. Engine block 14 includes awater jacket 604 surrounding two of the cylinders 22. A similar setup isused for the two cylinders on the opposite side of the engine 10 (notshown). Water jacket 604 includes a channel 606 in which cooling fluidflows around the first and second exhaust pipes 600 and 602 and thecylinders 22 in the manner described below to remove heat from thesystem. Cooling fluid enters water jacket 604 from a pump (not shown) atcooling intake port 608. The cooling fluid flows at a constant rate inthe directions indicated by arrows A1 and A2 through channel 606 aroundboth cylinders 22 as indicated by arrows B1 and B2 and C1 and C2. Thecooling fluid flows into cooling outtake port 610 as show by arrows D1and D2. From cooling outtake port 610, the cooling fluid is returned tothe pump where it is cooled and pumped back into cooling intake port608. In one embodiment, water jacket 604 and cooling jacket 178described above are integrated and the coolant flows around both thecylinders 22, the first and second exhaust pipes 600 and 602, and thecylinder heads as described above before returning to the pump.

Referring now to FIG. 16, a cross-sectional view of engine 10 and waterjacket 604 taken along line XVI-XVI of FIG. 15 is shown. First exhaustpipe 600 includes a top portion 612 and a bottom portion 614. Similarly,second exhaust pipe 602 includes a top portion 616 and a bottom portion618. In one embodiment, channel 606 includes a first branch 620 passingover the top portions 612 and 616 and a second branch 622 passing underthe bottom portions 614 and 618. The first and second branches mergetogether on the opposite sides of exhaust pipes 600 and 602 to reformuniform channel 606. In this embodiment, the cooling fluid flows intowater jacket 604 and begins to flow around cylinders 22 as indicated byarrows A1 and A2 in figure 15. As the cooling fluid approaches the firstand second exhaust pipes 600 and 602, one portion of the cooling fluidflows over the top portions 612 and 616 as indicated by arrows E1 and E2while another portion of the cooling fluid is diverted to flow under thebottom portions 614 and 618 as indicated by arrows F1 and F2 and G1 andG2. After the cooling fluid passes separately over the top and bottomportions of exhaust pipes 600 and 602, the two fluid flows merge tocontinue flowing around cylinders 22 as described above. Having coolingfluid flow over the top and bottom portions of the exhaust pipes 600 and602 allows for bidirectional cooling and prevents the bottom portions614 and 618 from overheating that can occur when the exhaust pipes areonly cooled from the top.

Referring to FIG. 19, a schematic illustration of an embodiment ofengine 10 as a dry sump engine that includes an oil sump pump orscavenge pump 420 to remove oil and air from within the crankcase 18.Referring to FIG. 19, the engine 10 also includes an oil tank 422 and ascavenge discharge line 424 that provides fluid communication betweenthe crankcase 18, the scavenge pump 420, and the oil tank 422. Engine 10further includes a supply oil pump 426, an oil pressure regulator 428,and an oil cooler or heat exchanger 430. The oil supply pump 426supplies oil to the engine block 14 and crankcase 18 from the oil tank422 during operation of the engine 10. The oil pressure regulator 428bleeds or allows a portion of oil to travel back to the oil tank 422 ifthe discharge pressure of the supply pump 426 exceeds a predeterminedvalue. For example, in one construction, the oil pressure regulator 428is set such that the oil pressure within the heat exchanger 430 does notexceed about 150 psi. An oil filter 432 is disposed between the oil tank422 and the engine block 14 to filter oil supplied to the engine block14 from the tank 422.

Referring to FIGS. 19 and 20, a schematic view of an embodiment ofengine 10 wherein turbocharger 3 includes a compressor 435 and a turbine436 that drives the compressor 435 using exhaust gas from the engine 10.An oil supply line 438 (FIG. 19) fluidly couples the turbocharger 3 andthe oil tank 422 to supply oil to the turbocharger 3. An oil return line440 fluidly couples the turbocharger 3 and the oil tank 422 to returnoil from the turbocharger 3 back to the oil tank 422. A pressure sensor442 and a temperature sensor 444 are in fluid communication with a mainoil supply line 446 to sense the pressure and temperature, respectively,of oil being supplied to the engine block 14, the crankcase 18, and theturbocharger 3.

Referring to FIG. 20, an air inlet 450 and an air filter 452 arearranged in series in an air inlet line 454 of the engine 10. Referringto FIG. 19, an air vent line 462 fluidly couples the oil tank 422 withthe air inlet 450 to vent the oil tank 422 to the air inlet line 454.

The engine 10 further includes a crankcase pressure regulator 466 thatis in fluid communication with the oil tank 422 and the crankcase 18 viaa crankcase breather line 468. The crankcase breather line 468 includesa first portion 470 that extends between the crankcase pressureregulator 466 and the crankcase 18 to provide fluid communicationbetween the crankcase 18 and the crankcase pressure regulator 466. Asecond portion 472 of the breather line 468 extends between the pressureregulator 466 and the oil tank 422 to provide fluid communicationbetween the pressure regulator 466 and the oil tank 422.

Referring to FIGS. 17 and 18, the crankcase pressure regulator 466includes a body 476. In one embodiment, the body 476 is formed to definea first internal passageway 478 and a second internal passageway 480that both extend through the body 476 of the pressure regulator 466. Thebody 476 further includes a first aperture 482 and a second aperture484. The first passageway 478 is defined as a flow path through thefirst aperture 482 and the second aperture 484. The second passageway480 is defined as a flow path through the first aperture 482 and thesecond aperture 484 such that the second passageway 480 is in a parallelarrangement to the first passageway 478. A first connector 486 ispartially located within the first aperture 482 in order to fluidlycouple the first aperture 482 with the crankcase 18 of the engine 10 viathe first portion 470 of the breather line 468. A second connector 488is partially located within the second aperture 484 to fluidly couplethe second aperture 484 with the oil tank 422 via the second portion 472of the breather line 468. While the first and second connectors 486 and488, respectively, are threaded nipples or bushings, in otherconstructions, any suitable connector can be utilized.

Furthermore, while FIG. 20 schematically illustrates the crankcasepressure regulator 466 connected to the crankcase breather line 468 atboth the connectors 486 and 488, the connectors 486 and 488 can beutilized to directly couple the pressure regulator 466 to either thecrankcase 18 or the oil tank 422. For example, in one construction thepressure regulator 466 can be mounted on the oil tank 422 using anaperture 490 of the body 476 and the second connector 488 can beconnected to the oil tank 422. Of course, in other constructions, othersuitable arrangements of the pressure regulator 466 within the flow pathof the crankcase 18, crankcase breather line 468, and the oil tank 422can be utilized.

The body 476 of the pressure regulator 466 further includes a firstauxiliary aperture 494 and a second auxiliary aperture 496. The firstand second auxiliary apertures 494 and 496 are utilized whilemanufacturing the pressure regulator 466 to access the passageways 478and 480 and other components within the pressure regulator 466. In oneembodiment, threaded plugs 498 and 500 are utilized to block or closethe apertures 494 and 496, respectively, after the requisitemanufacturing and assembling processes are completed within the body476.

The pressure regulator 466 further includes a first check valve 504 anda second check valve 506. The first check valve 504 includes a seat 508,which is integrally formed in the body 476. The first check valve 504further includes a valve member 510, and a biasing member 512. In oneembodiment, valve member 510 is a ball and biasing member 512 is a coilspring. The biasing member 512 contacts the first connector 486 to biasthe valve member 510 against the seat 508 or into a closed position ofthe valve 504. As will be discussed in more detail below, the firstcheck valve 504 regulates flow through the first passageway 478, and thefirst check valve 504 is arranged to allow fluid flow through the firstpassageway 478 in the direction of the arrows of FIG. 18 along the firstpassageway 478 while preventing fluid flow in the opposite direction.

The second check valve 506 includes a seat 514, which is integrallyformed in the body 476. The second check valve 506 further includes avalve member 516, and a biasing member 520. In one embodiment, valvemember 516 is a ball and biasing member 520 is a coil spring. Thebiasing member 520 of the second check valve 506 contacts the threadedplug 498 of the first auxiliary aperture 494 such that the valve member516 is biased against the seat 514 or into a closed position of thevalve 506. As will be discussed in more detail below, the second checkvalve 506 regulates flow through the second passageway 480, and thesecond check valve 506 is arranged to allow fluid flow through thesecond passageway 480 in the direction of the arrows of FIG. 18 alongthe second passageway 480 while preventing fluid flow in the oppositedirection. While the check valves 504 and 506 in the illustratedconstruction are ball-type check valves, it should be understood thatother types of valves and check valves can be utilized.

In one embodiment, the crankcase pressure regulator 466 includes apressure sensor 524. The pressure sensor 524 is in fluid communicationwith the first and second passageways 478 and 480, respectively, suchthat pressure sensor 524 is operable to measure the pressure within thecrankcase 18 regardless of the position (i.e., open or closed) of thefirst and second check valves 504 and 506, respectively.

Referring to FIG. 20, during operation of the engine 10, ambient air forcombustion is drawn through the air inlet 450, then through the airfilter 452 by the compressor 435 of the turbocharger 3. The compressor435 is driven by the turbine 436 to compress the combustion air. Theturbine 436 is driven by exhaust gases from the engine 10 that aredelivered to the turbine 436 by an exhaust line 530. The compressedcombustion air then travels through the intercooler 2 and supercharger 1before entering the combustion chamber of the engine 10.

Concurrently, referring now to FIG. 19, the scavenge pump 420 removesair and oil from within the crankcase 18 through the scavenge dischargeline 424, which generally reduces the pressure within the crankcase 18below the ambient pressure. The air and oil removed by the scavenge pump420 can include air and oil from the combustion chamber that bypassesthe piston rings.

The first check valve 504, which is biased into the closed position,inhibits make-up air from entering the crankcase 18 through thecrankcase breather line 468 until the pressure within the crankcase 18reaches a predetermined average lower level. Thus, the average pressurewithin the crankcase 18 is reduced and maintained below ambientpressure, particularly during low power operation of the engine 10. Thefirst check valve 504 remains closed until the average crankcasepressure is less than the predetermined average lower level. When thecrankcase pressure is less than the predetermined lower level, thepressure within the oil tank 422 (about ambient pressure) acting againstthe valve member 510 overcomes the force of the biasing member 512 tolift the valve member 510 from the seat 508 to open the first valve 504to allow make-up air to flow into the crankcase 18 in order to maintainthe air pressure within the crankcase 18 above the predetermined averagelower level.

The pistons 26, 330 being alternatively drawn into the crankcase 18 andthe pistons 26, 330 being pushed into the cylinders during the normalcompression and combustion strokes of the engine 10 generate a pressurewave in the crankcase 18. In one construction of the engine 10, thispressure wave is about +/−4 psi. In such a construction, the biasingmember 512 of the first check valve 504 can be chosen such that thefirst check valve 504 opens when the average pressure within thecrankcase 18 is about −6 psi. Alternatively stated, the first checkvalve 504 opens to allow make-up air to pass through the firstpassageway 478 when the pressure within the crankcase 18 is 6 psi lessthan the pressure within the oil tank 422, which is about ambientpressure. Therefore, if the pressure wave is about +/−4 psi, theinstantaneous pressure within the crankcase 18 will oscillate betweenabout −10 psi and −2 psi and the peak of the pressure wave will notexceed ambient pressure (e.g., 0 psi). In the illustrated construction,the make-up air is drawn from the oil tank 422 through the breather line468. While in the construction of the pressure regulator 466 discussedabove, the first check valve 504 opens at −6 psi, in other constructionsthe first check valve 504 can open at an average pressure greater thanor less than −6 psi. For example, the engine seals and/or the amplitudeof the pressure wave generated by piston oscillation may make adifferent opening average pressure for the check valve 504 moredesirable.

During operation of the engine 10, particularly during low poweroperation of the engine 10, the pressure within the intake manifold isrelatively low or near atmospheric pressure. Thus, in the constructiondescribed above, the instantaneous pressure within the crankcase 18 doesnot exceed about −2 psi or remains lower than the intake manifoldpressure. As a result, the amount of oil that is forced by pressure fromthe crankcase 18 toward the intake manifold is greatly reduced.

During high power operation of the engine 10, the pressure within theintake manifold can be relatively high. Furthermore, as discussed above,the pressure regulator 466 lowers the average pressure within thecrankcase 18. As a result, there can be an excessive amount of air thatleaks past the piston rings and into the crankcase 18. While thescavenge pump 420 removes air from the crankcase 18, the leakage may beat such a rate that the pump 420 is unable to remove a sufficient amountof air to maintain a negative (i.e., less than ambient) pressure withinthe crankcase 18. If the pressure within the crankcase 18 exceeds apredetermined average level, the second check valve 506 opens to allowair to pass through the second passageway 480 and to the oil tank 242and vent 462 thereby venting the crankcase 18 to the air inlet line 454(FIG. 20). The second check valve 506 remains closed until the averagecrankcase pressure is greater than the predetermined level. When thecrankcase pressure is greater than the predetermined level, the pressurewithin the crankcase 18 acting against the valve member 516 overcomesthe force of the biasing member 520 to lift the valve member 516 fromthe seat 514 to open the second valve 506.

In one construction, the biasing member 520 of the second check valve506 is chosen such that the second check valve 506 opens when theaverage pressure within the crankcase is about 0.2 psi above ambientpressure. Of course in other constructions, the second check valve 506can be designed to open at more or less than 0.2 psi.

The foregoing description of the present invention has been presentedfor purposes of illustration and description. Furthermore, thedescription is not intended to limit the invention in the form disclosedherein. Consequently, variations and modifications commensurate with theabove teachings in skill or knowledge of the relevant art, are withinthe scope of the present invention. The embodiments described herein arefurther intended to explain the best modes known for practicing theinvention and to enable others skilled in the art to utilize theinvention as such, or other embodiments and with various modificationsrequired by the particular applications or uses of the presentinvention. It is intended that the appended claims are to be construedto include alternative embodiments to the extent permitted by the priorart. It is understood that the invention disclosed and defined hereinextends to all alternative combinations of two or more of the individualfeatures mentioned or evident from the text and/or drawings. All ofthese different combinations constitute various alternative aspects ofthe present invention.

For purposes of this disclosure, the term “coupled” means the joining oftwo components directly or indirectly to one another. Such joining maybe stationary in nature or movable in nature. Such joining may beachieved with the two members and any additional intermediate membersbeing integrally formed as a single unitary body with one another orwith the two members or the two members and any additional member beingattached to one another. Such joining may be permanent in nature oralternatively may be removable or releasable in nature.

While the current application recites particular combinations offeatures in the claims appended hereto, various embodiments of theinvention relate to any combination of any of the features describedherein whether or not such combination is currently claimed, and anysuch combination of features may be claimed in this or futureapplications. Any of the features, elements, or components of any of theexemplary embodiments discussed above may be used alone or incombination with any of the features, elements, or components of any ofthe other embodiments discussed above.

What is claimed is:
 1. An engine, comprising: a piston; an engine blockassembly with a cylinder having a sleeve within which the piston islocated, an intake port, and an exhaust port; a head assembly coupled tothe engine block assembly; and a fireplate fixed between the sleeve andthe head assembly.
 2. The engine of claim 1, wherein the engine blockassembly and the cylinder are made from aluminum and the fireplate ismade from a stainless steel.
 3. The engine of claim 1, wherein thesleeve is a metal composite and includes a second intake port and asecond exhaust port proximate to a bottom end of the cylinder.
 4. Theengine of claim 1, wherein the sleeve is a composite sleeve that issolution and precipitation heat treated and wherein the composite sleevehas a minimum tensile strength of 33 KSI and a minimum yield of 27 KSI.5. The engine of claim 1, wherein the sleeve is a metal composite thatincludes a silicon carbide particulate and a nickel coated graphite, andwherein the sleeve is fabricated from aluminum and has a steel coatedinternal surface.
 6. The engine of claim 1, further comprising femalethreads on the engine block assembly and male threads on the headassembly, wherein the head assembly is theadedly coupled to the engineblock assembly.
 7. The engine of claim 1, further comprising a fluidflow channel in the head assembly, wherein a first branch in the fluidflow channel passes over the exhaust port and a second branch in thefluid flow channel passes under the exhaust port.
 8. The engine of claim1, further comprising a head spring between the head assembly and thefireplate, the head spring creating a biasing force on the fireplate. 9.The engine of claim 8, wherein the head spring is made from a stainlesssteel and is a Belleville spring with a shallow conical disk having ahole through a center of the Belleville spring.
 10. An engine,comprising: an engine block having a cylinder with an intake port and anexhaust port; a fluid flow channel that cools the engine block and islocated within the engine block adjacent to one of the intake port andthe exhaust port; a head assembly including a fuel flow channel to coolthe head assembly; a fuel reservoir coupled to the fuel flow channel; afuel injector assembly coupled to the fuel flow channel on the headassembly, to transport a fuel to an injector tip in the intake port andreturn excess fuel from the injector tip to a fuel reservoir; and apiston positioned to oscillates within the cylinder.
 11. The engine ofclaim 10, further comprising a cooling cap with a substantially annularcoolant groove that couples to the head assembly, wherein the coolingcap is adjustably positioned around the head assembly.
 12. The engine ofclaim 11, further comprising an inlet port and an outlet port on thecooling cap, wherein the inlet port and the outlet port are notdiametrically opposed around the substantially annular coolant groove.13. The engine of claim 12, further comprising a first coolingpassageway in the substantially annular coolant groove extending in afirst direction from the inlet port to the outlet port, and a secondcooling passageway in the substantially annular coolant groove extendingin a second direction from the inlet port to the outlet port, whereinthe first cooling passageway is shorter than the second coolingpassageway.
 14. The engine of claim 13, wherein a flow rate of the fuelthrough the first cooling passageway is restricted, and wherein the flowrate through the substantially annular coolant groove in the firstdirection is correlated to a length of the first cooling passageway inthe first direction relative to a length of the second coolingpassageway in the second direction of the substantially annular coolantgroove.
 15. The engine of claim 11, further comprising a cooling jacketin the engine block, wherein the fuel is transported from the fuelsource to the cooling jacket to remove heat from the engine block, andthen from the cooling jacket to the substantially annular coolant grooveof the cooling cap on the head assembly to remove heat from the headassembly.
 16. The engine of claim 15, wherein the fuel returns to thecooling jacket in the engine block before the fuel flows back to thefuel source.
 17. The engine of claim 16, wherein the fluid flow channelincludes a first branch passing over the exhaust port and a secondbranch passing under the exhaust port, and wherein the fuel flow channelincludes a third branch passing in a first substantially annulardirection between the intake port and an outlet port and a fourth branchpassing in a second substantially annular direction between the intakeport and the outlet port.
 18. An engine, comprising: an engine blockhaving four or more cylinders, each cylinder has an intake port and anexhaust port; a fluid flow channel located adjacent to one of thecylinders within the engine block adjacent to one of the intake port andthe exhaust port that cools the engine block; a sleeve fixed within eachcylinder of the engine block; a head assembly having a fuel flow channelto supply fuel to each cylinder, the fuel flow channel supplies fuel tothe intake port of the cylinder such that the fuel cools the headassembly; a fuel injector assembly coupled to the fuel flow channel onthe head assembly, the fuel injector assembly transports a fuel to aninjector tip in each cylinder and returns excess fuel from the injectortip to a fuel source; a fireplate located between the sleeve on eachcylinder and the head assembly; and a piston within the sleeve of eachcylinder, the piston configured to oscillate within the sleeve.
 19. Theengine of claim 18, wherein the fluid flow channel includes a firstbranch passing over the exhaust port and a second branch passing underthe exhaust port and the fuel flow channel includes a third branchpassing in a first substantially annular direction between an inlet portand an outlet port on the head assembly and a fourth branch passing in asecond substantially annular direction between the inlet port and theoutlet port.
 20. The engine of claim 18, further comprising asupercharger coupled to each intake port that compresses air prior toentering each cylinder.